Mobile communications are carried out using mobile radio communications units or handsets known in the art as ‘mobile stations’ which include a transmitter to convert messages or information input by a user into radio frequency (RF) signals for transmission to a distant receiver, and a receiver to convert received RF signals from a distant transmitter back into information which can be understood by the user. Many components of the transmitter and receiver are common components usually forming a single transceiver unit.
In a mobile station, the function of sending and receiving an RF signal via an air interface to and from a distant transceiver is carried out by a component referred to in the art as an antenna or aerial. In general, an antenna is a device which converts an electrical signal oscillating at RF frequency into a radiated electromagnetic energy signal and vice versa. In this specification, ‘RF’ is generally understood to mean wireless frequencies of greater than 2 kHz, e.g. up to 300 GHz. In many cases the RF energy will have a frequency of from 100 KHz to 100 GHz.